In a number of early articles in defense of Aldo Leopold's land ethic, the philosopher J. Baird Callicott appeals to a theory of moral sentiments to connect facts and values: from descriptions of ecological relationships he hopes to derive prescriptions as to how we should make decisions about environmental change, with moral sentiments as the middle term.
I've long had doubts about this move, and I've taken up the matter in a number of papers I've had published. The most basic problem is that, while the moral sentiments view introduced by Hume and cultivated by Darwin offers important insight into human moral experience, on its own it seems to undermine the very possibility of ethical deliberation.
Here's Callicott, from In Defense of the Land Ethic (Albany: State University of New York Press, 1989), p. 127:
Leopold urges upon us the conclusion, [that] we ought to ‘preserve the integrity, stability, and beauty of the biotic community.’ Why ought we? Because (1) we all generally have a positive attitude toward the community or society to which we belong; and (2) science has now discovered that the natural environment is a community or society to which we belong, no less than to the human global village.
Callicott set up the pattern for this sort of practical syllogism with an argument about smoking:
1) We all have a strong inclination to preserve our own health.
2) Smoking is harmful to human health.
Therefore, 3) you ought not to smoke.
Start with two facts - one about the world, one about human psychology - and end with a moral injunction. Is yields ought. It's very tidy.
Well, not so tidy, really. I've pointed out elsewhere that Callicott smuggles an ought into the ises. Suppose, for example, a teenager denies the validity of the practical syllogism regarding smoking on the grounds that he or she does not value life all that highly just now. Callicott responds by revising the first claim, to the effect that "psychologically normal" people in fact share such an inclination and that, if someone does not share it, then psychological counseling may be prescribed. In other words, people ought to share this particular inclination, and we have a duty to make sure they do.
With this argument, Callicott trapped himself. How is this new, smuggled-in ought to be justified? By appeal to further moral sentiments that all normal people ought to share? or by appeal to something that is not a moral sentiment? That's his choice: he must either allow himself to fall into an infinite regress, or he must contradict the theory of moral sentiments on which he has pinned his hopes for the land ethic.
As I say, I've dealt with this all this in the past. The only reason I revisit it is that I've put a new twist on the argument. It occurred to me that a similar practical syllogism could be derived from any widely-shared sentiment or inclination bequeathed to us by natural selection. So . . .
1. All psychologically normal males have a strong inclination to seek orgasm at any opportunity.
2. [Pick one: a) a random hook-up, b) hiring a prostitute, c) clandestine homosexual activity in public restrooms, d) date rape] is an opportunity to attain orgasm.
Therefore, 3. You ought to [pick one . . .].
Depending on your own inclinations, I would assume you would see following through on some or all of the options listed in 2 as irresponsible and/or reprehensible and/or icky. Still, claim 1 is fairly obviously true, and claim 2 is fairly obviously true, as stated. If Callicott's practical syllogism on behalf of the land ethic is cogent, then so is this practical syllogism on behalf of [pick one: promiscuity, deviance, criminal wrongdoing.]
Now, you may be thinking, this is hardly fair. Even allowing that psychologically normal males have a strong inclination to seek orgasm, the whole point of morality is to keep such "low" or "base" inclinations in check, subordinating them to our "higher" and more refined inclinations. Darwin sets this up well in The Descent of Man, where he presents morality as what inevitably happens to a social animal that happens to develop intellect: we can remember, we scold each other, we can feel remorse, and so we can master ourselves and resolve to do better in the future.
But this precisely is the Achilles' heel of moral sentiments theory: it's hard to know what it could mean to exercise self-control when, on a purely empiricist account, the self is really just a bundle of sensations and sentiments. On this account, moral deliberation occurs when two sentiments clash, and the decision is made when the stronger sentiment prevails. The "self" has nothing to do with it. Reason, which according to Hume is only "the slave of the passions," cannot intervene on its own account.
In any case, the theory of moral sentiments seems to leave all psychologically normal males with a prima facie duty to pursue orgasm at all costs. Of course, this would have to be balanced against our prima facie duty to our own long-term well-being, our duty to care about the well-being of others, our duty to the broader community. But, if Hume, Darwin, and Callicott are to be believed on this point, the balance will have to find itself while "we" stand back and watch.
May the stronger sentiment win.